54. Deniition of Pulmonate Mollusks. 
Urocycius. 
Urocyclus Kirkit, Gray. Mozambique. Mr. J. 5. Gibbons 
Jaw (pl. XVI, fig. K) very low, slightly arcuate; ends scarcely attenuated, 
blunt; anterior surface without ribs; no median projection to the cutting- 
edge; a strong muscular attachment. 
mane ual membrane (pl. XVII, fig. N) with tricuspid centrals, bicuspid 1a 
erals, as in Zonites, and aculeate marginals, all of which are bifid. 
The figure shows one central, one lateral, and two marginals. 
Nanina. 
The species of this genus have tricuspid centrals, bicuspid 
laterals, and bifid aculeate marginals. I have examined from 
Mauritius (Consul Pike),— 
Nanina Caldwelli, Benson. 
IN, Ikapsonns, Wemecleny, (rll, IU, ine, 1D.) 
IN, copied, Inssie, (Welle JEL, iti, (O',) 
ING amnjoloeaien, INO, (Vell, Il, inies 18), ) 
N. stylodon, Pir. 
The last cannot be retained in Hrepta, a sub-genus of Helia, 
where it was placed by Von Martens. All the above have similar 
dentition. Also from Mauritius— 
N. phailyrina, Morelet. 
Though this species agrees in other respects with the above-named, the mem- 
brane is very broad, the teeth exceedingly numerous, arranged in oblique 
rows. The centrals, which I am confident of having seen, are small, narrow, 
high. The other teeth are the same in form to the edge of the membrane. 
They appear to have the usual aculeate form of the marginal teeth in Nanina; 
but instead of narrowing towards the cutting-point, they are broadly and 
obliquely truncated, reflected, and minutely denticulated. This lingual mem- 
brane is also figured by Semper (Phil. Archip., pl. V1, f. 85); but his figures 
give more the impression of the usual Nanina marginals with denticulated 
side and bifid points. The teeth are, however, so exceedingly numerous 
and small that it is very difficult to understand them. 
Nanina vnversicolor, Fér. 
Also from Mauritius, has the character of animal, jaw, and lingual mem- 
brane of Nanina, so that it cannot be retained in Caracolus, a sub-genus of 
Felix. 
Nanina nilitaris, 
Of same locality, for the same reasons cannot be retained in Stylodon, and— 
